Author Topic: Theoretical Question  (Read 9637 times)

Offline 1967KaiserM715

  • Junior Member
  • ***
  • Posts: 914
  • 1985 GMC K1500 w/ 6.5 TD
Re: Theoretical Question
« Reply #15 on: January 21, 2018, 12:57:55 PM »
1986 C2500?

That's your issue if it isn't a typo, a 2500 frame is thinner and lighter then the 3500 frames.

Sent from my SM-S920L using Tapatalk

Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Online VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 18980
Re: Theoretical Question
« Reply #16 on: January 21, 2018, 05:20:10 PM »
Again, unless someone can provide you destructive facts and figures it's a guessing game. For every action there is an equal and opposite reaction. The only thing anyone can offer you is an opinion.
,                           ___ 
                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3324
Re: Theoretical Question
« Reply #17 on: January 21, 2018, 06:39:11 PM »
1) Why do you use/want a slide in vs. a travel trailer?   Because the easy solution might be to get one of those trailers that is a camper AND has section in the back for tools/toys etc.......because you were thinking about getting a new camper anyways.......?

2) Even with 4.10 gear i think (not positive, but think) the highest GVWR is 8600 for 3/4 ton?   So you'll be WAY over capacity anyways with a 4000 lbs slide in camper?

So why not just use the c-3500?

3) Doing further research, it appears that ALL the gm intermediate convertables got a boxed frame AND el caminos also did.   But i suspect this was more for stiffening than to increase weight capacity?

Not sure what to tell ya.............

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #18 on: January 22, 2018, 09:22:36 PM »
Cool, thanks guys. Yes, the 2500 frame is a lighter frame, except for the crew cabs. Those got the 1-ton frames.

Since everyone keeps jumping ahead of my question. Here's the theoretical plan:

1. Box the C-channel frame. Fab up some beefed up crossmembers.
2. Replace the rear axle with a D80.
3. Replace the front axle with a D70 (yes, I intend to convert to 4x4).
4. Replace the 454 with a Ramjet 502 crate engine.
5. Replace the TH400 with a Supermatic 4L85

That should be plenty tough to do what I have in mind. Everything but #1 is easily do-able, "theoretically" speaking. It's #1 where things get tricky. A boxed 1-ton frame looks like it would be beefier than a 3500 HD frame. When I ask around amongst my redneck farmer and gearhead 4x4 friends, they seem to think it would be plenty stout. BUT I haven't crawled under a 3500 HD to measure frame heights or wall thicknesses. Also, given the difficulty of removing a frame to re-engineer it after failure, and the general expense level involved, a guy would really hate to be wrong. So I'm looking for a "multitude of counselors," if you will.

Mind you, this is all theoretical. Most likely, nothing will ever happen and the truck will return to dust sitting in my yard hundreds of years from now. I'll buy a used mall crawler and grouse about how much I dislike the new trucks every time I get in it, while realizing that I do like dome lights that turn themselves off when you leave the door open, and that backup cams are really helpful for hitching trailers. I'll drive it by the C2500 every day and wish for what might have been.

Still, I can dream...
« Last Edit: January 22, 2018, 09:26:49 PM by Dr_Snooz »
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Stewart G Griffin

  • Senior Member
  • ****
  • Posts: 3324
Re: Theoretical Question
« Reply #19 on: January 25, 2018, 08:07:35 PM »
i think #3 may answer the question, but do you have to have a slide in camper, or will a travel trailer do?

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #20 on: January 27, 2018, 09:36:51 AM »
Has to be a slide in camper. I need to be able to pull a tool trailer. I need to be able to pull up to a disaster recovery site fully self-contained and ready to rock.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline 1967KaiserM715

  • Junior Member
  • ***
  • Posts: 914
  • 1985 GMC K1500 w/ 6.5 TD
Re: Theoretical Question
« Reply #21 on: January 27, 2018, 11:11:04 AM »
I would start with some bolt on frame stiffeners or crossmembers. Make sure the bolts are snug in the hole-bets way to do this is to drill the hole undersized and ream to fit the bolt. Use 7/16" grade 8 hardware.

Frame stiffeners can be as simple as a 3x3 or even 4x4 angle iron, at least 16-18" long. Bolted to the outer edge of the frame.

If you want to add some rigid crossmembers, just move the frame stiffeners to the interior of the frame then create the crossmember.

Some big rigs use a double C frame rail (c-channel in a c-channel.) And extra crossmembers-all bolted in, to create a stronger frame.

The strongest crossmember to reduce flexing between frame rails is an 'x' pattern. A straight member will allow more twisting and movement.

Sent from my SM-S920L using Tapatalk

Current Vehicles:1985 GMC K10(Daily) 1991 GMC K2500(Daily) 1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
 1986 Chevy K30(under repair)

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13319
  • Family is not an important thing. It's everything.
Re: Theoretical Question
« Reply #22 on: February 01, 2018, 07:09:34 PM »
im going to add to whats been said, your springs, brakes and axles are the weak point to these trucks. take my crew cab 350/4l80e 205 1 ton with single rear axle, its gvwr is 9400 my buddies a dually 454 th400/205 that has the same frame but different axles with bigger pads. its gvwr is around 11000.

the weight of a goose neck is going to be over the rear axle so the frame will have little impact there. the gvwr is also biased on the trans/engine. take i believe its a 79 1 ton they also came with an inline 6. but its gvwr is lower than the 350. so more springs+more power+better trans will give you a higher gvwr but DOT wont care unless you been re-certified to haul that much more weight.

if you want the best answer go to a spring shop they'll tell you what you need to know and will tell you what is needed
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13319
  • Family is not an important thing. It's everything.
Re: Theoretical Question
« Reply #23 on: February 01, 2018, 07:18:53 PM »
also keep in mind the difference in GAWR, GVWR and GVCW.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=33169.msg282039#msg282039

the trailer will be hauling most of the weight your truck is only pulling its weight + the tongue weight. my crew cab 1 ton is 9400 LBS but my curb weight with the cummins and tools is 7300. so i can effectively haul 2000 lbs in tongue weight and still be ok by GVWR
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #24 on: April 04, 2018, 12:38:20 AM »
Updating thread with some new data. I went truck shopping with my brother last week and had a chance to crawl under a 2008 Ford F-350 Super Duty. The truck is listed with a GVWR of ~11k and a GCWR of up to ~33k depending on engine and axle ratio. The surprising thing for me was that the frame was a plain old ordinary C-channel. It was as thick as my 1-ton frame and not as tall. Basically, it wasn't as strong as what I have, but still rated for waaay more weight. So that would confirm what you guys are saying, that the frame isn't really the big issue here.

Only recently have the 3500 HDs gone to a fully boxed frame, but even there, I think the cab and chassis configurations still have a C-channel in the rear for bolting up aftermarket box beds and the like. So again, the frame isn't the big concern.

I know on my '90, the brakes are my BIG limiting factor. They heat right up under load. The frame gets wiggly under load and the suspension bushings wear out quickly, but the frame hasn't had any trouble at all.



Time to rant:

Why were we shopping for trucks you ask? A few years ago, my brother lost his mind and bought a Ford. Specifically, he bought a 95 Ford F-350 Power Stroke (with the Int'l engine). He thinks it's all that, and most owners do love that engine. It IS impressive: a giant 7.3L diesel with 400+ ft-lbs of torque that still gets 16-20 MPG. The ENGINE is great, but the thing burned up 4 [manual] transmissions in one year hauling a heavy travel trailer. So he's doing without the travel trailer while he gives it all a re-think. He's looking for a trans that won't burn up under heavy load, aaaaaaannnndddd... He ain't finding one. Everyone on every discussion board knows that the much vaunted Power Stroke likes to blow up whatever transmission you put behind it. Which makes me wonder how Ford's engineers did not know what every guy on every discussion board seems to know? Of course they knew! It's so typical for Ford to spec something they knew would not hold up under normal use, just to save a few dollars. They think nothing of making you remove the intake manifold to change a coolant hose, or pull the body to change head gaskets, or spec'ing an engine that grenades transmissions, or a gas tank that blows up on impact, or a car that rolls over and kills people after a routine blowout. When their wickedness gets into the papers, they throw lawyers and PR flacks at the problem. What a disgusting company. How does a business with such total contempt for its customers keep from going broke???

The best part is that for vacations, my brother's driving the wife's Suburban and staying at motels. In so doing, he finds out that he can drive almost twice as long because the Suburban is so much quieter, whereas the noisy, stinky Power Stroke beats him into submission in a relatively short time.

The moral of the story: never buy a Ford.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #25 on: April 04, 2018, 12:39:18 AM »
BTW, does anyone know if any kind of tempering or heat-treating was done to these old frames at the factory? How about on the new HD frames?
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #26 on: June 24, 2018, 06:33:00 PM »
I was driving past the Chevy dealership last week when I slammed on the brakes and flipped a quick illegal U-turn. They finally had a 3500 HD pickup on the lot. It was not a cab and chassis, which still uses C-channel frames, but a pickup with the boxed frame. I can confirm that the new, fully boxed 3500 HD frame is basically just a boxed K3500 frame. Now I didn't spend a lot of time under there, and I didn't have a dial calipers with me. I didn't take any measurements, or look at all the brackets or anything. I just eyeballed the frame rails, and those are essentially the same dimensions as a K3500 frame but with a full box.

So if you're hankering for a 3500 HD that you can actually see out of, then box the frame on your K or C.
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60

Offline Dr_Snooz

  • Junior Member
  • ***
  • Posts: 590
  • "I like to take hammers, and just break stuff"
Re: Theoretical Question
« Reply #27 on: June 24, 2018, 09:07:38 PM »
Honestly, I don't understand why they haven't been boxing these frames for a long, long time. I looked under a 2500 HD a few years ago. It was just a beefed up C-channel frame. There was so much extra metal under that thing, it was crazy. The boxing is a much better use of materials.

Anyway, as far as I'm concerned, the answer to my original question is that YES, boxing a square body frame will make it as strong as one of the new 3500 HD truck frames.

Thanks guys!
1989 Chevy Suburban V-2500, 5.7L, TH400

1990 Chevy C-3500 Ext. Cab, 7.4L, 3L80

2009 Chevy Silverado 1500 WT 4WD, 4.8L, 4L60